Reinforced composites are rapidly growing in popularity for such applications as automobile components, boat hulls and fishing rods. Reinforced polymeric composites can be formed from a polymeric matrix material, reinforcing material and any other desired components in a variety of ways. For example, for a thermosetting matrix material, a composite can be formed by molding, pultrusion, filament winding, hand lay-up or spray-up. For a thermoplastic matrix material, suitable methods for forming a composite include direct molding or extrusion compounding followed by injection molding.
As molding processes become more sophisticated and raw material costs escalate, the need for an inexpensive reinforcement which provides adequate physical properties in a composite, such as strength, modulus and impact resistance, has become increasingly important.
The coating on the reinforcement provides an interface between the reinforcement material, such as glass fiber strand, and the polymeric matrix material of the composite. The compatibility of the coating with the reinforcement material and the polymeric matrix material and strength of the bonding at the interface are important considerations in the selection of coating components. The amounts and types of components used in the coating composition influence the cost of the reinforcement. It is desirable to include less expensive components in the coating composition to lessen cost while maintaining performance of the reinforcement in the composite.
U.S. Pat. No. 4,762,750 discloses sized fiber bundles coated with an impregnating composition having one or more elastomeric polymers that are essentially free of hydrocarbon diene and chlorine functionalities and one or more crosslinking materials (see Abstract). The elastomeric polymer can be a polyurethane or an ethylene-containing interpolymer formed from ethylene monomer and one or more polar comonomers. See column 6, lines 21-38.
U.S. Pat. No. 5,182,784 discloses an aqueous coating composition for glass strands consisting essentially of 2-50 weight percent of a thermoplastic polyurethane latex, 3-55 weight percent of a first curable acrylic latex and 0.5-10 weight percent of a paraffin wax emulsion or a second curable acrylic latex. See column 1, lines 29-39.
In reinforcement of composites, including thermoplastics such as nylon, it is desirable to simplify and diversify the coating process and reduce the cost of coating composition components while providing coated reinforcements which have acceptable physical performance in the composite.